Students live in disgusting houses. The houses aren't disgusting when they move in. They're usually quite clean. But it doesn't take long for the bacteria to take over.
This summer, my eldest is leaving the place where he's lived for two years.
"It's very sad," he said.
Sad? I think they're getting out just in time. We went to pick up all his stuff at the weekend – he's staying on for a few parties – and I'm still in a state of shock.
The living room was wall-to-wall beer bottles. The carpet on the stairs was covered in mud, dust, and what looked like decomposing biscuit. There was broken glass in the hall.
I won't describe the toilet. No one should ever see a toilet like that, let alone relive the experience.
"We'll give it a good clean before we go," said my eldest, seeing my expression. Just in time. I reckon they were only a few days off a visit from environmental health.
"What worries me," I said to my husband as we set off back to London in the car, "is that he'll think it's OK to live like that at home, too."
My husband looked fiercely at the motorway. "You'll have to have a word with him."
I don't think one word will do. Unless it's something on the lines of 'NO!' or 'HELP!' or 'POLICE!'
I'm reconciled to teenagers having messy bedrooms. My daughter's room is like an impenetrable rainforest in which lost treasures from days long gone are buried under trailing fronds of silky fabric.
"But at least you keep all the mess in one place," I said to her. "Your brother lets it expand until it takes over the whole house. I don't think he even sees it."
"Maybe you should take a photograph of what you'd like each room to look like," she said, "and stick it to the door. Then he can make a comparison on the way out."
Maybe I'll have to. But I'm still confused. Why does he find keeping a house clean so difficult?
I ring my mother to complain. I know she'll understand.
"It sounds," she says, "just like the house you lived in as a student. I remember how shocked your father was. There were hundreds of dirty milk bottles all lined up on the draining board."
Her memory's not what it was.